Like many successful movements, this one started slow. A few people were excited about it, but there were skeptics, even dissenters. Recently, though, rubbing oil on your face has become accepted beauty practice. Once produced only by small brands, face oils are now on drugstore shelves and department store counters. So how do you use them? Let us count the ways: Massaged in every morning as a skin-smoothing base for makeup (or just sunscreen). Mixed with your favorite foundation (about one drop of oil to three pumps of makeup) when you want sheer coverage. Smoothed over a retinoid cream at night to prevent irritation and flaking. Patted over the flyaways around your hairline. (Hey, why not?) If you're convinced this is a beauty crusade worth joining, try one of our four favorite ways to get involved: